Drilling Rig System Having Improved Electrical Subsystem

ABSTRACT

In embodiments, a drilling rig system includes a rig unit having rig equipment and a rig electrical subsystem configured for electrical communication with the rig equipment and including a rig electrical subsystem input transformer, an electrical system including a primary power supply subsystem remote from the rig unit, and an intermediate electrical subsystem.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/481,227, filed Apr. 6, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/593,776, filed Jan. 9, 2015, which is acontinuation-in-part of U.S. patent application Ser. No. 14/554,882filed on Nov. 26, 2014.

FIELD OF THE INVENTION

The disclosure relates to improved drilling rig systems, such as fordrilling wells at plural discrete locations at a drilling site. Those ofordinary skill will appreciate that need exists for drilling rig systemshaving an improved electrical subsystem.

BACKGROUND OF THE INVENTION

The disclosure relates to improved drilling rig systems, such as fordrilling wells at plural discrete locations at a drilling site. Those ofordinary skill will appreciate that need exists for drilling rig systemshaving an improved electrical subsystem.

BRIEF SUMMARY OF THE INVENTION

Embodiments provide a drilling rig system that may have a stationaryprimary power subsystem and movable rig unit that can be relocatedacross a foundation pad between plural discreet drilling locations at adrilling site. A drilling rig system can include only a singleintermediate conductor, or a single composite intermediate cablestructure, extending between a stationary primary power subsystem andmovable rig unit. Embodiments provide a drilling rig system that mayhave a stationary primary power subsystem and movable rig unit with asingle power conductor member extending therebetween that is simplifiedand of reduced size and number, and of improved reliability, and mayprovide for more efficient operation with reduced time and labor, andwith improved safety. In embodiments, a drilling rig system may have astationary primary power subsystem and a movable rig unit that can berelocated across foundation pad between plural discreet drillinglocations, and that can include only a single first releasable powerconnector assembly between a primary power supply subsystem andintermediate electrical subsystem, and only a second releasable powerconnector assembly between intermediate electrical subsystem and a rigelectrical subsystem of the movable rig unit, and that are simplifiedand of reduced size and number, and of improved reliability, and providefor more efficient operation with reduced time and labor, and withimproved safety. Embodiments provide the advantages of eliminatingnumerous 600 volt alternating current (“VAC”) intermediate cables thatwould otherwise extend from a primary power supply subsystem to amovable rig unit. Embodiments provide for simplified and more efficientuse of the foundation pad by personnel and mobile equipment, such as towmotors, at a drilling site without requiring personnel to navigate overor around, or to physically move and reposition and connect ordisconnect a plurality of 600 VAC intermediate cables. Embodimentsprovide the benefit of eliminating numerous drag links and festoons forhandling numerous intermediate cables when relocating the rig unit.Embodiments provide the benefit of eliminating numerous electrical plugsand receptacles, and thus reducing high maintenance and resultingmaintenance and repair downtime for same. Embodiments provide thebenefit of enabling use of 600 VAC equipment at the primary power supplysubsystem and rig unit. Embodiments provide the benefit of eliminating alarge number of power cables and draglinks or festoons necessary to handlong multiple cables, and minimizing the number of power connectorassemblies and components, such as releasable plug and receptacle powerconnector assemblies. Embodiments provide the benefit that power can betransferred to a movable rig unit at 4160 VAC over a single three-phaseintermediate conductor or cable. Embodiments provide the benefit that adrawworks variable frequency drive (VFD), a top drive variable frequencydrive and related control equipment can be included in a local equipmentroom (LER) that may be combined with the drillers control cabin on themovable rig unit. Embodiments provide the benefit that the control logicequipment for the drawworks, top drive and rig mounted equipment islocated in the drillers control cabin and can communicate back via wire,fiber or wireless. Embodiments provide control wiring from rig mountedequipment that runs only a short distance from the rig equipment to thedrilling control unit, such as from local equipment room (LER) of thedriller's control cabin, and thus can eliminate or reduce communicationproblems associated with long control leads and numerous intermediateconnections.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the disclosed subjectmatter will be set forth in any claims that are filed later. Thedisclosed subject matter itself, however, as well as a preferred mode ofuse, further objectives, and advantages thereof, will best be understoodby reference to the following detailed description of an illustrativeembodiment when read in conjunction with the accompanying drawings,wherein:

FIG. 1 is a schematic illustration of a drilling rig system 10 in anembodiment.

FIG. 2 is a one-line diagram of drilling rig system 10 in an embodimentillustrated in FIG. 1.

FIG. 3 is a one-line diagram of a drilling rig system 710 in anembodiment.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Reference now should be made to the drawings, in which the samereference numbers are used throughout the different figures to designatethe same components.

FIG. 1 is a schematic illustration of a drilling rig system 10 accordingto an embodiment. It will be understood that in other embodiments (notshown) a drilling rig system of different arrangement can practicesubject matter herein disclosed.

Drilling rig system 10 is located at a drilling site. Referring to FIG.1, the drilling site may include plural discrete drilling locations 18a, 18 b, and 18 c where wells are to be drilled. The drilling site maybe, for example, a location where plural discrete hydrocarbon wells,located in close proximity to one another, are to be drilled. Wellslocated in close proximity to one another may be used to accessdifferent depths of a formation.

In the embodiment illustrated in FIG. 1, drilling rig system 10 mayinclude a foundation pad 20 installed on the ground at the drillingsite. Although foundation pad 20 can be arranged differently, and canhave different dimensions, in the particular embodiment illustrated inFIG. 1, foundation pad 20 is substantially rectangular and spans theground to encompass the plural discrete drilling locations 18 a, 18 b,18 c at the drilling site. Although different materials of constructioncan be used, in the embodiment illustrated in FIG. 1, foundation pad 20is formed of concrete. It will be understood that in other arrangements,foundation pad 20 can be formed of any material that provides sufficientsupport for operation of drilling rig system 10.

Referring to FIG. 1, drilling rig system 10 includes rig unit 30supported on foundation pad 20. Rig unit 30 may be configured andoperable to perform drilling functions and operations. It will beunderstood that different embodiments of drilling rig system 10 caninclude any suitable rig unit 30, including rig units of differentconfigurations, arrangements, and appearances, and can be of differentmanufacture. Rig unit 30 can include rig structure such as, for example,a mast (not shown) extending in a vertical direction above drillinglocation 18 a where a respective well is to be drilled. It will beunderstood that rig unit 30 is relocatable or moveable across foundationpad 20 from drilling location 18 a to be positioned for drilling wellsat the other of the plural discrete drilling locations 18 b and 18 c. Inthe specific position illustrated in FIG. 1, rig unit 30 is positionedor located on foundation pad 20 for drilling a well at drilling location18 a. It will be understood that rig unit 30 may include a relocationsubsystem (not shown) configured for operation to enable relocationmovement of rig unit 30 across foundation pad 20. A suitable relocationsubsystem (not shown) may include, for example, a walking mechanism, aset of wheels, a set of tracks, or combinations thereof. It will beunderstood that the relocation subsystem may be configured and operablefor moving or walking rig unit 30 across foundation pad 20 between theplural discrete drilling locations 18 a, 18 b, and 18 c. Rig unit 30 mayinclude a drilling floor (not shown) configured for personnel to standand walk upon for performing rig work such as, for example, making upand breaking apart threaded connections between pipe joints, andchanging out down-hole tools.

Referring to FIG. 1, rig unit 30 can include rig equipment 50 configuredand operable to perform respective functions. It will be understood thatrig equipment 50 can include electro-mechanical equipment 54 such as,for example, hydraulic equipment. The rig equipment 50 may include, byway of example and without limitation, top drives, hoists, draw works,pipe tongs, joint elevators, electro-mechanical equipment, wrenchingequipment, electric motors, pumps, rotary tables, lifting equipment, andcombinations thereof. Referring to FIG. 2, in an embodiment thereinillustrated, rig equipment 50 includes top drive 64 and draw works 68.

Referring to FIG. 1, rig unit 30 can include rig electrical subsystem 70configured for electrical communication with the rig equipment 50. Itwill be understood that the rig electrical subsystem can be configuredto deliver power to rig equipment 50. Referring to FIG. 2, the rigelectrical subsystem can include a rig electrical subsystem inputtransformer 74. In the specific embodiment illustrated in FIG. 2, rigelectrical subsystem input transformer 74 can be located onboard rigunit 30. It will be understood that, in other arrangements (not shown),rig electrical subsystem input transformer 74 may be physically locatedoff-board, in close physical proximity to the major structure of rigunit 30. The rig electrical subsystem input transformer 74 may beconfigured to receive intermediate power from an intermediate electricalsubsystem 300. The rig electrical subsystem input transformer 74 isconfigured to transform intermediate power at high voltage to rig powerat rig operating voltage, where the rig operating voltage is lower thanthe high voltage of the intermediate power. In the particular embodimentillustrated in FIG. 2, for example, rig electrical subsystem inputtransformer 74 is configured to transform intermediate power receivedfrom intermediate electrical subsystem 300 at 4160 VAC to rig power atrig operating voltage 600 VAC. It will be understood that theintermediate power or rig power can differ from the particular valuesset forth in the specific embodiments illustrated herein. In anembodiment illustrated in FIG. 2, rig electrical subsystem inputtransformer 74 can provide rig power at 600 VAC on a rig subsystemconductor 71. It will be understood that in embodiments (not shown), arig electrical subsystem input transformer can provide rig power at 480VAC on a rig subsystem conductor to rig equipment configured foroperation at 480 VAC.

Referring to FIG. 2, rig electrical subsystem 70 may include a motorcontroller 76 for providing power to rig equipment 50 such as, orincluding, a respective electric motor. Any suitable motor controllermay be used. In the specific embodiment illustrated in FIG. 2, motorcontroller 76 includes suitable variable frequency drive 78, 79. It willbe understood that motor controller 76, such as variable frequency drive78, 79, receives rig power and provides controlled power to respectiverig equipment 50 such as, or including, a respective electric motor. Inthe particular embodiment illustrated in FIG. 2, variable frequencydrive 78 is configured to deliver conditioned power to top drive 64 forenabling operation thereof. In the particular embodiment illustrated inFIG. 2, variable frequency drive 79 is configured to deliver conditionedpower to draw works 68 for enabling operation thereof.

Referring to FIG. 2, rig electrical subsystem 70 may include rig controlsubsystem 90 configured for controlling functions and operations of rigequipment 50 and remote subsystems 200. Rig control subsystem 90 mayinclude a data communications subsystem 110. It will be understood thatdata communications subsystem 110 may include a suitable datacommunications cable 114 in communication with data network equipment(not shown) such as, for example, one or more servers (not shown) anddistributed data sources (not shown) such as, for example, remote sensordevices and network-enabled remote devices (not shown). Datacommunications cable 114 can extend, for example, from servers in adriller's cabin (not shown) on-board rig unit 30. Again referring toFIG. 2, data communications cable 114 can extend, for example, to datasources and network-enabled remote devices (not shown) located at rigequipment 50, motor controller 76, and variable frequency drive 78, 79on-board rig unit 30. Data communications cable 114 can extend from rigunit 30 to off-board equipment and systems such as, for example, remotesubsystems 200 including intermediate electrical subsystem 300, primarypower subsystem 400 and mud pumping system 500.

Referring to FIG. 2, rig control subsystem 90 may include controlcircuits 120. It will be understood that control circuits 120 mayinclude suitable control circuit cables 124 in low voltage electricalcommunication with controllable equipment (not shown). Controllableequipment can include, for example, one or more programmable logiccontrollers (PLC's), switches, and motor controllers such as, forexample variable frequency drives. Control circuit cables 124 canextend, for example, from a drilling control unit in a driller's cabinon-board rig unit 30 to controllable equipment such as programmablelogic controllers (PLC's), switches, and motor controllers such asvariable frequency drives, located on-board rig unit 30. Control circuitcables 124 can extend from rig unit 30 to off-board equipment andsystems such as, for example, remote subsystems 200 includingintermediate electrical subsystem 300, primary power subsystem 400 andmud pumping system 500.

It will be understood that rig unit 30 may include a driller's controlunit (not shown) that can enable a controls and information interface(not shown) for personnel such as a driller. In some embodiments, forexample, a driller's control unit may be housed in a driller's controlcabin (not shown). A driller's control unit can include rig equipmentcontrols (not shown) and data communications subsystem equipment andcontrols (not shown) configured to enable control and operation ofdrilling rig system 10 including, for example, rig equipment 50 andremote subsystems 200. It will be understood that control and operationsfunctions of drilling rig system 10, rig unit 30, rig equipment 50 andremote subsystems 200 may be performed by automated systems, or byautomated systems under control, or partial control, of personnel suchas a driller. It will be understood that a driller's control cabin maybe configured to house a driller for operating a control interface, andmay include a driller's control chair having, for example, one or morejoystick-type input devices.

Referring to FIG. 2, it will be understood that rig electrical subsystem70 may include tertiary circuits 96 in electrical communication withtertiary equipment (not shown) such as, for example, lights and othertertiary equipment.

Referring to FIG. 2, drilling rig system 10 includes primary powersupply subsystem 400 remote from rig unit 30. In the particularembodiment illustrated in FIG. 2, the primary power supply subsystem 400can be configured to provide primary power at 600 VAC (for example) tothe intermediate electrical subsystem 300. It will be understood thatprimary power supply subsystem 400 in embodiments of disclosed subjectmatter can be of different configuration or arrangement from thatspecifically illustrated in FIG. 2. In embodiments as illustrated inFIG. 2, primary power supply subsystem 400 may include at least oneprimary generator 410 a, 410 b, 410 c configured to provide primarypower at 600 VAC (for example) to the intermediate electrical subsystem300. In an embodiment the primary power supply subsystem 400 can includea powerhouse unit 430 (shown in FIG. 1), which may be skid-mounted,located on foundation 20 remote from the rig unit 30, wherein thepowerhouse unit 430 includes the at least one primary generator 410 a,410 b, 410 c. In a particular embodiment illustrated in FIG. 2, primarypower supply subsystem 400 may include three primary generators 410configured to provide three-phase primary power at 600 VAC (for example)on primary conductor 420 to the intermediate electrical subsystem 300.It will be understood that primary power supply subsystem 400 caninclude a main Power Control Room (not shown).

It will be understood that in embodiments as illustrated in FIG. 2,primary power supply subsystem 400 can include mud system power line 440configured to provide 600 VAC to mud pumping system 500. As shown inFIG. 2, mud pumping system 500 can include one or more mud pumps 550.Primary power supply subsystem 400 may include a suitable variablefrequency drive 450, or other suitable motor controller as describedherein for rig unit 30, configured for providing power to each mud pump550 to enable operation thereof. It will be understood that respectivecontrollers, such as PLC's 460, of control subsystem 600 can providecontrol and data communication with mud pumps 550, and with control andsensing elements of variable frequency drive 450. It will be understoodthat PLC's 460 can be in communication with the driller's cabin of rigunit 30 over control cabling as elsewhere described for sensing andcontrolling operation of mud pumps 550 and mud pumping system 500.

Referring to FIG. 2, in an embodiment drilling rig system 10 can includeintermediate electrical subsystem 300 configured for electricalcommunication between the primary power supply subsystem 400 and the rigelectrical subsystem 70. It will be understood that intermediateelectrical subsystem 300 is configured to carry power from the primarypower supply subsystem 400 to the rig electrical subsystem 70 forpowering the rig equipment 50. In a particular embodiment illustrated inFIG. 2, the intermediate electrical subsystem 300 can be configured toprovide intermediate power at 4160 VAC (for example) to the rigelectrical power subsystem 70, and particularly to rig electricalsubsystem input transformer 74 of same. It will be understood thatintermediate electrical subsystem 300 in embodiments of disclosedsubject matter can be of different configuration or arrangement fromthat specifically illustrated in FIG. 2. In embodiments as illustratedin FIG. 2, intermediate electrical subsystem 300 may include anintermediate conductor 310 configured to carry and provide intermediatepower at 4160 VAC (for example) to the rig electrical subsystem 70. Itwill be understood that intermediate conductor 310 can include a singlepaired set of intermediate conductor members (not shown), wherein thepaired set includes both a supply conductor member and a returnconductor member (not shown). It will be understood, that in aparticular embodiment as shown in FIG. 2, intermediate conductor 310 maybe provided in a single intermediate conductor unit configured to carry4160 VAC.

Referring to FIG. 2, in an embodiment intermediate electrical subsystem300 can include an intermediate subsystem input transformer 320. Inembodiments, intermediate subsystem input transformer 320 can beconfigured for electrical communication with the primary power supplysubsystem 400 for receiving primary power therefrom at 600 VAC (forexample) and for providing intermediate power at 4160 VAC onintermediate conductor 310. In an exemplary embodiment illustrated inFIG. 2, intermediate subsystem input transformer 320 can be locatedremote from rig unit 30 and in close proximity to primary power supplysubsystem 400. It will be understood that, in other arrangements (notshown), intermediate subsystem input transformer 320 may be physicallyco-located on a skid structure with primary power supply subsystem 400,or in a common housing or cabinet structure with same. The intermediatesubsystem input transformer 320 can be configured to receive primarypower from primary power supply subsystem 400. The intermediatesubsystem input transformer 320 can be configured to transform primarypower at primary voltage to intermediate power at high voltage, wherethe primary voltage is lower than the high voltage of the intermediatepower. In a particular embodiment as illustrated in FIG. 2, for example,intermediate subsystem input transformer 320 is configured to transformprimary power received from primary power supply subsystem 400 at 600VAC to intermediate power at 4160 VAC. It will be understood that thelevels or voltage of intermediate power or primary power can differ fromthe particular values set forth in the specific embodiments illustratedherein.

Referring to FIG. 1, it will be understood that drilling rig system 10can include a first releasable power connector assembly 800 configuredfor providing electrical communication between primary power supplysubsystem 400 and intermediate electrical subsystem 300. A suitablefirst releasable power connector assembly 800 may include, for example,a plug and receptacle combination. It will be understood that, inembodiments as illustrated in FIG. 1, first releasable power connectorassembly 800 can be configured for providing electrical communicationbetween primary power supply subsystem 400 and intermediate electricalsubsystem 300. It will be understood that, in a particular embodiment,first releasable power connector assembly 800 can be embodied by theelectrical primary power supply subsystem 400 including a firstreleasable connector member (not shown) and by the intermediateelectrical subsystem 300 including a second releasable connector member(not shown) configured for releasable mating engagement. Drilling rigsystem 10 can include a second releasable power connector assembly 810configured for providing electrical communication between rig electricalsubsystem 70 and intermediate electrical subsystem 300. It will beunderstood that, in embodiments as illustrated in FIG. 1, secondreleasable power connector assembly 810 can be configured for providingelectrical communication between rig electrical subsystem 70 andintermediate electrical subsystem 300. It will be understood that, in aparticular embodiment, second releasable power connector assembly 810can be embodied by the rig electrical subsystem 70 including a firstreleasable connector member (not shown) and by the intermediateelectrical subsystem 300 including a second releasable connector member(not shown) configured for releasable mating engagement. It will beunderstood that in embodiments, drilling rig system 10 can bedifferently configured to embody the subject matter and may include, forexample, releasable power connector assemblies other than asspecifically illustrated in FIG. 1.

Referring to FIG. 1, drilling rig system 10 may include conductorcarrier reel 330 configured to carry intermediate conductor 310 inspooled relationship therewith. In embodiments as illustrated in FIG. 1,intermediate electrical subsystem 300 may include conductor carrier reel330 configured to carry intermediate conductor 310 in spooledrelationship therewith, wherein the conductor carrier reel 330 issupported for rotation about a conductor carrier reel axis 331 forplaying the intermediate conductor 310 in spooled relationship relativethereto. In embodiments as illustrated in FIG. 2, conductor carrier reel330 can be supported for relocation movement with the rig unit 30,wherein the conductor carrier reel 330 is configured for playing in theintermediate conductor 310 thereupon during relocation movement of therig unit 30 across foundation pad 20 toward the primary power supplysubsystem 400, and wherein the conductor carrier reel 330 is configuredfor playing out the intermediate conductor 310 therefrom duringrelocation movement of the rig unit 30 across foundation pad 20 awayfrom the primary power supply subsystem 400. It will be understood thatrelocation movement of the rig unit 30 across foundation pad 20 canoccur when moving the rig unit 30 between the plural discrete drillinglocations 18 a, 18 b, 18 c for drilling wells at the same. It will beunderstood that in embodiments of disclosed subject matter, theconductor carrier reel 330 at conductor carrier reel axis 331 can besupported in fixed relationship to the rig unit 30, wherein theconductor carrier reel 330 is configured for playing the intermediateconductor 310 spooled thereupon relative to the rig unit 30 duringrelocation of the rig unit 30 across the foundation pad 20. Inembodiments as shown in FIG. 2., for example, the conductor carrier reel330 can be supported by the rig unit 30 on a suitable frame (not shown),wherein conductor carrier reel axis 331 is supported in fixedrelationship to the rig unit 30 for conductor carrier reel 330 to berelocated with rig unit 30. It will be understood that intermediateconductor 310 can extend from spooled relationship with conductorcarrier reel 330 to provide electrical communication with rig electricalsubsystem 70 at second releasable power connector assembly 810 (shown inFIG. 1).

Referring to FIG. 1, drilling rig system 10 may include control cablingcarrier reel 350. In embodiments, intermediate power supply subsystem300 may include discrete control cabling 340, wherein the discretecontrol cabling 340 is discrete from the intermediate conductor 310. Itwill be understood that discrete control cabling 340 may include atleast one of: data communication cable 114 configured for communicatingdata between the rig unit 30 and remote subsystems 200 includingequipment remote from the rig unit 30, and control circuit wiring 124that may extend offboard from rig unit 30 for enabling control of remotesubsystems 200 including equipment remote from the rig unit 30. Asillustrated in FIG. 2, drilling rig system 10 may include intermediatepower supply subsystem 300 including control cabling carrier reel 350configured to carry the discrete control cabling 340 in spooledrelationship therewith, wherein the control cabling carrier reel 350 issupported for rotation about a control cabling carrier reel axis 351 forplaying the discrete control cabling 340 in spooled relationshiprelative thereto. In embodiments as illustrated in FIG. 2, controlcabling carrier reel 350 can be supported for relocation movement withthe rig unit 30, wherein the control cabling carrier reel 350 isconfigured for playing in the control cabling 340 thereupon duringrelocation movement of the rig unit 30 across foundation pad 20 towardthe primary power supply subsystem 400, and wherein the control cablingcarrier reel 350 is configured for playing out control cabling 340therefrom during relocation movement of the rig unit 30 acrossfoundation pad 20 away from the primary power supply subsystem 400. Itwill be understood that relocation movement of the rig unit 30 acrossfoundation pad 20 can occur when moving the rig unit 30 between theplural discrete drilling locations 18 a, 18 b, 18 c for drilling wellsat the same. It will be understood that in embodiments of disclosedsubject matter, the control cabling carrier reel 350 at conductorcarrier reel axis 351 can be supported in fixed relationship to the rigunit 30, wherein the control cabling carrier reel 350 is configured forplaying the control cabling 340 spooled thereupon relative to the rigunit 30 during relocation of the rig unit 30 across the foundation pad20. In embodiments as shown in FIG. 2., for example, the control cablingcarrier reel 350 can be supported by the rig unit 30 on a suitable frame(not shown), wherein control cabling carrier reel axis 351 is supportedin fixed relationship to the rig unit 30 for control cabling carrierreel 350 to be relocated with rig unit 30. It will be understood thatcontrol cabling 340 can extend from spooled relationship with controlcabling carrier reel 350 to provide electrical control circuit and datacommunication with rig electrical subsystem 70 at a first releasablecontrol connector assembly 830 (shown in FIG. 1). It will be understoodthat control cabling 340 can extend from spooled relationship withcontrol cabling carrier reel 350 to provide electrical control circuitand data communication with elements of remote control subsystem 600 ata second releasable control connector assembly 820 (shown in FIG. 1).

An exemplary embodiment of a drilling rig system 710 is illustrated inFIG. 3. It will be understood that drilling rig system 710 may besubstantially identical to drilling rig system 10 (shown in FIG. 1 andFIG. 2) except as otherwise described in this paragraph or shown in FIG.3. Drilling rig system 710 can include intermediate power supplysubsystem 300 including composite intermediate cable structure 370. Thecomposite intermediate cable structure 370 can include both intermediateconductor and control cabling. It will be understood that intermediateconductor can be substantially identical to intermediate conductor 310of drilling rig system (shown in FIGS. 1 and 2). It will be understoodthat control cabling can be substantially identical to discrete controlcabling 340 of drilling rig system 10 (shown in FIGS. 1 and 2). It willbe understood that drilling rig system 710 may include a first compositereleasable power and control connector assembly 760 configured toprovide electrical communication, and control circuit and datacommunication, from remote subsystems 200 including primary power supplysubsystem 400 to intermediate electrical subsystem 300. It will beunderstood that drilling rig system 710 may include a second compositereleasable power and control connector assembly 770 configured toprovide electrical communication, and control circuit and datacommunication, from to intermediate electrical subsystem 300 to rigelectrical system 70. It will be understood that drilling rig system 710may include a conductor carrier reel 350 configured to carry thecomposite intermediate cable structure 370 in spooled relationshiptherewith. It will be understood that the conductor carrier reel 350 canbe supported for rotation for playing the composite intermediate cablestructure 370 in spooled relationship relative thereto.

Embodiments provide a drilling rig system having a stationary primarypower subsystem 400 and movable rig unit 30 that can be relocated acrossfoundation pad 20 between plural discreet drilling locations 18 a, 18 b,18 c that can include only a single intermediate conductor 310, or asingle composite intermediate cable structure 370 extending betweenstationary primary power subsystem 400 and movable rig unit 30.Embodiments provide a drilling rig system having a stationary primarypower subsystem 400 and movable rig unit 30 with a single powerconductor member therebetween that is simplified and of reduced size andnumber, and of improved reliability, and provide for more efficientoperation with reduced time and labor, and with improved safety.Embodiments similarly provide a drilling rig system having a stationaryprimary power subsystem 400 and movable rig unit 30 that can berelocated across foundation pad 20 between plural discreet drillinglocations 18 a, 18 b, 18 c that can include only a single firstreleasable power connector assembly between primary power supplysubsystem 400 and intermediate electrical subsystem 300, and only asecond releasable power connector assembly between intermediateelectrical subsystem 300 and rig electrical subsystem 70 of movable rigunit 30, that are simplified and of reduced size and number, and ofimproved reliability, and provide for more efficient operation withreduced time and labor, and with improved safety. Embodiments providethe advantages of eliminating numerous 600 VAC intermediate cables thatwould otherwise extend from primary power supply to a movable rig unit.Embodiments provide for simplified and more efficient use of thefoundation pad by personnel and mobile equipment, such as tow motors, ata drilling site without requiring personnel to navigate over or around,or to physically move and reposition and connect or disconnect aplurality of such 600 VAC intermediate cables. Embodiments provide thebenefit of eliminating numerous drag links and festoons for handlingnumerous intermediate cables when relocating the rig unit. Embodimentsprovide the benefit of eliminating numerous electrical plugs andreceptacles, and thus reducing high maintenance and resultingmaintenance and repair downtime for same. Embodiments provide thebenefit of enabling use of 600 VAC equipment at the primary power supplysubsystem and rig unit. Embodiments provide the benefit of eliminating alarge number of power cables and draglinks or festoons necessary to handlong multiple cables, and minimizing the number of power connectorassemblies and components, such as releasable plug and receptacle powerconnector assemblies. Embodiments provide the benefit that power can betransferred to the rig at 4160 VAC over a single three-phaseintermediate conductor or cable. Embodiments provide the benefit that adrawworks variable frequency drive (VFD), a top drive variable frequencydrive and related control equipment can be included in a local equipmentroom (LER) that may be combined with the drillers control cabin formovement with the rig unit. Embodiment provide the benefit that thecontrol logic equipment for the drawworks, top Drive and rig mountedequipment is located in the drillers control cabin and can communicateback via wire, fiber or wireless. Embodiments provide control wiringfrom rig mounted equipment that runs only a short distance from the rigequipment to the drilling control unit, local equipment room (LER) ofthe driller's control cabin, and thus can eliminate or reducecommunication problems associated with long control leads and numerousintermediate connections.

What is claimed is:
 1. A drilling rig power system comprising: a movablerig electrical subsystem electrically coupled to a plurality of rigequipment, the movable rig electrical subsystem comprising a rigelectrical subsystem input transformer for transforming intermediatepower at a high voltage to rig power at a voltage that is less than thehigh voltage; a stationary primary power supply subsystem remote fromthe movable rig electrical subsystem; and an intermediate electricalsubsystem comprising an intermediate subsystem input transformerelectrically coupled to the stationary primary power supply subsystemfor transforming primary power at another voltage that is less than thehigh voltage of the intermediate power to the high voltage of theintermediate power, and an intermediate conductor electrically coupledto the intermediate subsystem input transformer and the rig electricalsubsystem input transformer.
 2. The drilling rig power system of claim1, wherein the another voltage of the primary power is at or below 690Volts AC, and the high voltage of the intermediate power is at or above2300 Volts AC.
 3. The drilling rig power system of claim 1, wherein thevoltage of the rig power is at or below 690 Volts AC.
 4. The drillingrig power system of claim 1, wherein the intermediate conductorcomprises no more than a set of conductor members for carryingthree-phase electrical current.
 5. The drilling rig power system ofclaim 1, wherein the intermediate electrical subsystem comprises anotherintermediate conductor electrically coupled to the intermediatesubsystem input transformer and the rig electrical subsystem inputtransformer.
 6. The drilling rig power system of claim 1, wherein theintermediate electrical subsystem comprises a conductor carrier reelconfigured to support the intermediate conductor for rotation about aconductor carrier reel axis during extension or retraction of theintermediate conductor.
 7. A drilling rig power system comprising: amovable rig electrical subsystem electrically coupled to a plurality ofrig equipment, the movable rig electrical subsystem comprising a rigelectrical subsystem input transformer; a stationary primary powersupply subsystem remote from the movable rig electrical subsystem; andan intermediate electrical subsystem comprising no more than twothree-phase intermediate conductors electrically coupled to thestationary primary power supply subsystem and the rig electricalsubsystem input transformer.
 8. The drilling rig power system of claim7, wherein the intermediate electrical subsystem enables the movable rigelectrical subsystem to travel away from the stationary primary powersupply subsystem while maintaining electrical communication with thestationary primary power supply subsystem.
 9. The drilling rig powersystem of claim 7, wherein the no more than two three-phase intermediateconductors are retractable to enable the movable rig electricalsubsystem to travel toward the stationary primary power supply subsystemwhile maintaining electrical communication with the stationary primarypower supply subsystem.
 10. The drilling rig power system of claim 7,wherein the no more than two three-phase intermediate conductors areconfigured to carry intermediate power at a high voltage.
 11. Thedrilling rig power system of claim 7, wherein at least one of the nomore than two three-phase intermediate conductors is included in acomposite intermediate cable structure that comprises the intermediateconductor and a control cable for communicating data between a rig unitand subsystems remote from the rig unit.
 12. The drilling rig powersystem of claim 7, wherein the rig electrical subsystem inputtransformer transforms intermediate power received through the no morethan two three-phase intermediate conductors at a high voltage to rigpower at a voltage lower than the high voltage.
 13. The drilling rigpower system of claim 7, wherein the intermediate electrical subsystemcomprises a conductor carrier reel configured to support the no morethan two three-phase intermediate conductors for rotation about aconductor carrier reel axis during extension or retraction of theintermediate conductor.
 14. A method of powering a movable drilling rigunit, comprising: transmitting primary power at a voltage that is lessthan a high voltage from a stationary power supply subsystem to anintermediate subsystem input transformer; transforming the primary powerat the intermediate subsystem input transformer into intermediate powerat the high voltage; transmitting the intermediate power from theintermediate subsystem input transformer to a rig electrical subsysteminput transformer on the movable drilling rig unit through a highvoltage intermediate conductor; transforming the intermediate power atthe rig electrical subsystem input transformer into rig power at anothervoltage that is lower than the high voltage; and transmitting the rigpower from the rig electrical subsystem input transformer to a pluralityof rig equipment on the movable drilling rig unit.
 15. The method claim14, wherein the another voltage of the primary power is at or below 690Volts AC, and the high voltage of the intermediate power is at or above2300 Volts AC.
 16. The method claim 14, wherein the voltage of the rigpower is at or below 690 Volts AC.
 17. The method claim 14, wherein thehigh voltage intermediate conductor comprises no more than a set ofconductor members for carrying three-phase electrical current.
 18. Themethod claim 14, comprising: transmitting the intermediate power fromthe intermediate subsystem input transformer to the rig electricalsubsystem input transformer on the movable drilling rig unit through anadditional high voltage intermediate conductor.
 19. A method of poweringa movable drilling rig unit, comprising: transmitting primary power froma stationary power supply subsystem to a plurality of rig equipment on amoveable drilling rig unit through no more than two three-phaseintermediate conductors.
 20. The method of claim 19, comprising:supporting the no more than two three-phase intermediate conductors on aconductor carrier reel for rotation about a conductor carrier reel axisduring extension or retraction of the no more than two three-phaseintermediate conductors.